package com.bdqn.t350.util;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

//@WebServlet("/ImageServlet")
@WebServlet(name = "ImageServlet",urlPatterns = "/ImageServlet")
public class ImageServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;


    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");


        BufferedImage bfi = new BufferedImage(80, 25, BufferedImage.TYPE_INT_RGB);
        Graphics g = bfi.getGraphics();
        g.fillRect(0, 0, 80, 25);


        //验证码字符范围
        char[] ch = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789".toCharArray();
        Random r = new Random();
        int index;
        StringBuffer sb = new StringBuffer(); //保存字符串
        for (int i = 0; i < 4; i++) {
            index = r.nextInt(ch.length);
            g.setColor(new Color(r.nextInt(255), r.nextInt(255), r.nextInt(255)));
            Font font = new Font("宋体", 30, 20);
            g.setFont(font);
            g.drawString(ch[index] + "", (i * 20) + 2, 23);
            sb.append(ch[index]);
        }


        // 添加噪点
        int area = (int) (0.02 * 80 * 25);
        for (int i = 0; i < area; ++i) {
            int x = (int) (Math.random() * 80);
            int y = (int) (Math.random() * 25);
            bfi.setRGB(x, y, (int) (Math.random() * 255));
        }


        //设置验证码中的干扰线
        for (int i = 0; i < 6; i++) {
            //随机获取干扰线的起点和终点
            int xstart = (int) (Math.random() * 80);
            int ystart = (int) (Math.random() * 25);
            int xend = (int) (Math.random() * 80);
            int yend = (int) (Math.random() * 25);
            g.setColor(interLine(1, 255));
            g.drawLine(xstart, ystart, xend, yend);
        }
        System.out.println("生成的字符串：" + sb.toString());
        HttpSession session = request.getSession();  //保存到session
        session.setAttribute("verificationCode", sb.toString());
        ImageIO.write(bfi, "JPG", response.getOutputStream());  //写到输出流
    }

    /**
     * 获取随机的颜色值，r,g,b的取值在Low到High之间
     *
     * @param L 左区间
     * @param R 右区间
     * @return 返回随机颜色值
     */
    private static Color interLine(int Low, int High) {
        if (Low > 255)
            Low = 255;
        if (High > 255)
            High = 255;
        if (Low < 0)
            Low = 0;
        if (High < 0)
            High = 0;
        int interval = High - Low;
        int r = Low + (int) (Math.random() * interval);
        int g = Low + (int) (Math.random() * interval);
        int b = Low + (int) (Math.random() * interval);
        return new Color(r, g, b);
    }
}
